1. Field of the Invention
The field of the invention relates to circuitry and signal processing as used in radar exciters, radar receivers and similar types of equipment and in particular to digital circuitry functioning as an analog frequency doubler, biphase modulation and/or blanking switch.
2. Description of the Prior Art
In radar related circuitry, such as radar exciters, radar receivers and similar types of equipment, the need for doubling the frequency of an analog signal, of biphase modulating the signal and controllably blanking or switching the signal is commonplace. The prior art has devised many different types of circuits to perform these functions, which circuits are typically comprised of complicated multiple stages of analog circuitry.
For example, frequency doubling is presently practiced by generating higher harmonics of the fundamental frequency through amplifiers or step recovery diodes followed by appropriate filtration. Biphase modulation is typically achieved by modulating the low port of a double balanced mixer. Signal blanking is typically performed by circuitry based on the operation of diode blanking switches While the performance of the prior art circuits is acceptable, their design is complex, usually entailing a high number of component parts, corresponding high expense, low reliability and the inherent requirement of relatively long design times and trouble shooting periods.
Therefore, what is needed is a simple design which can be used in radar equipment which is capable of frequency doubling, biphase modulation and/or blanking without entailing any of these defects of the prior art, which is capable of producing a high fidelity output signal and which can be simply and inexpensively manufactured in a LSI chip or hybrid.